Multi-scale biothermal and biomechanical behaviours of biological materials.

All living creatures, with no exception of humans, are subjected to an environment with both thermal and mechanical ‘loadings’. When the temperature is out of normal physiological range (e.g. in extreme heat or cold), biological activities fail to proceed in a normal way, resulting in injury or even death. On the other hand, in medicine, various therapeutic methods involving both thermal and mechanical loadings have been widely used to cure disease/injury at different scale levels from subcellular to the whole organ. The objective of these treatments is to induce injury precisely within the target but without affecting the surrounding healthy cells/tissues/organs. The effectiveness of these treatments is governed by the coupled thermal, mechanical and biological responses of the affected tissue: a favourable treatment results in a procedure with no lasting side effects. Biological systems function cooperatively across different spatial and temporal scales, from nanoscale biomolecules to microscale cells, and to macroscale tissues and organs. To understand the mechanisms of various biological functions, it is important to study biological systems at different scales. This Theme Issue of the Royal Society’s Philosophical Transactions A, entitled ‘Multiscale biothermal and biomechanical behaviours of biological materials’, aims to provide some insight into the biothermal–mechanical–neural behaviour at different scales. In this issue, biological behaviours at different scales are re-cast in engineering systems parlance. It focuses on the frontiers of this fast-growing field with emphasis on the thermal behaviour, mechanical behaviour, the coupled thermomechanical behaviour and corresponding neural response/signalling of biological materials at subcellular, cellular and tissue levels. This will enable better understanding of the underlying mechanism of biological behaviours and in turn support the growing fields of tissue engineering, cell therapeutics and disease treatment. The papers included in this issue show the broad scope of activities in this field with a series of reviews and original contributions. First, Zhu (2010) presents a review entitled ‘A multi-scale view of skin thermal pain: from nociception to pain sensation’ which describes an engineering view of skin thermal pain sensation covering molecular level (e.g. ion channel), cell level (e.g. nociceptor), tissue level (e.g. tissue thermomechanics) and whole organ level (human pain sensation). As a demonstration of the progress in multi-scale bioheat and mass transport, Xu et al. (2010) offer a review entitled ‘Multi-scale heat and mass transfer modelling of cell and tissue cryopreservation’, which describes a multi-scale